Decorative laminated plastics are commonly used as the surface material in the fabrication of countertops, table tops, interior and exterior wall panels, and other articles for residential and commercial use. The extensive use of laminated plastics in these applications is primarily due to their low cost, durability, impact and abrasion resistance, decorative clarity, resistance to heat and ultraviolet light, and resistance to mild chemicals.
Miller, in U.S. Pat. No. 3,266,971, taught improved clarity and smoothness characteristics of laminate surfaces, by use of a coating resin on the dried top surface of melamine-formaldehyde impregnated decorative print or protective overlay sheets. The coating resin, applied in the range of about 5 to 15 grams per square foot, contains a mixture of acrylic latex made from an alkyl ester of methacrylic acid; trialkyl monoamine; and a cross-linking agent selected from polyalkyl ethers of polymethylolmelamine or cycloaliphatic epoxy resins of the 3,4-epoxycyclohexylmethyl-3,4,epoxycyclohexane carboxylate type.
Pounds et al., in U.S. Pat. No. 3,345,248, taught improved wear, craze, and ultraviolet resistance for outdoor laminates, by use of a separate non-porous overlay sheet of polymethylmethacrylate, plasticized with styrenes or alkylacrylates, on top of a "B"-staged melamine-formaldehyde decorative print sheet. While these advances in the laminate art have solved many laminate problems, the single major deficiency of decorative laminates, resistance to strongly corrosive chemicals such as strong acids, bases, oxidizing agents, and powerful solvents, remains to be solved. Because of this deficiency, the use of decorative laminated plastics has been prohibited in environments where they are subject to being exposed to corrosive chemicals, such as in industrial laboratories, and in some hospital and school environments.